I'm opening a new thread for discussing Teachers functionality in the UU.
We have some Teacher related stuff in the specs:
http://www.total-knowledge.com/wiki/index.php/UU#Teacher
but I think it's time to extend it.
Here is the list of Teacher's activities that may be available in the UU:
1. Pass the comments to Student after he solves a problems and passes the
solution to Teacher.

We need to juxtapose this feature with Communication Tools in the specs

Ability to see list of all outstanding problems for
all Students

We don't have any administrative functionality in specs for now. There
is a question whether it makes sense to do it occasionally or better
leave an administrative tools (for teachers, schools, probably other
entities) block for future uu versions? Or we can set up some generic
interface for administrative features and leave it to implement for
community?

2. Add/Remove Students from his Course

See above + seems unacceptable as such.

3. Assign Course or any other UMO within a Course to a Student.

What that means? Recommendation or administration? If latter - see above.

4. Set grades(ratings) to a Student.

Same story. We don't have grades in specs.

5. Assign Students to certain difficulty levels within a Course.(Student
will be able to see only UMOs of certain difficulty level)

All the same. It is all for student's discretion as of today. We can
probably think about some specific channels where students can find
recommendations not from teacher only. I am not sure there is need for
this. We can discuss it though.

6. Ability to change any UMO difficulty level within a Course(No new
version should be created)

np

7. Sets the price for a Course

It is necessary feature. I believe we have it in specs.

8. Chooses his prefered language(s) for the Course from the list of
available languages for this Course.
9. Ability to hide(not update) from Student certain UMOs in the Course
that he teaches.

Don't need it. Actually, there is one more issue here postponed for
future versions: work flow. It relates to administration, but not entirely.